1. Field of the Invention
The invention relates generally to safes and bank protection and more particularly to wall and panel structures as may be used in modular vault structures.
2. Description of Related Art
Vault structures are classified according to their resistance to penetration attempts. Such resistance is measured in terms of the length of time required for a skilled person to gain access through the walls of a vault with the help of common mechanical tools, electric tools, cutting torches, or combinations thereof. Walls of a type referred to as Class 1 need to resist such attack for a period of one-half of an hour. Classes 2 and 3 pertain to vault structures having greater resistance to forced entry attempts. Vault structures classified in Classes 2 and 3 are those that have been tested and found to resist sustained attempts for one and two hours, respectively.
Though vaults with a greater penetration resistance would appear to be more desirable, in many instances the greater resistance to forced entries and the resulting delays greater than one-half hour are not needed because of other existing security precautions. In most secured areas, secure enclosures are protected by a combination of protective devices and arrangements, including security guard services in addition to electronic alarm systems. A reasonable resistance to any forced entry attempt would consequently allow effective countermeasures to be implemented within the period of delay offered by the wall of the secured enclosure.
In many instances light-weight wall panel structures for secured enclosures such as vaults may be preferred, particularly, when the vaults are to be built in upper stories of multi-story buildings. For such applications of light-weight wall panels for secured enclosures, an optimization of resistance within necessary weight limitations and also with reasonable budgetary constraints is desirable.
Currently existing light-weight wall panels for vaults are typically laminar structures including layers of hardwood planks interleaved with layers of expanded metal and pressboard or the like, all of which are joined, typically such as by nailing. A possible problem with existing prior art wall structures is that uniformly repeated structures tend to enhance the likelihood of success in attempts of forced entry, in that a successful intrusion through a first layer is likely to be repeated in less time with respect to a similar, second layer.